WHAT’S BEING CLAIMED:
- A new research tells what factors affect the Earth’s spin axis, as well as how much each of these factors contributes to the wobble.
- The three main factors for the changes in the Earth’s spin axis are melting glaciers, different environmental processes, and movement of the Earth’s mantle.
- Researchers of the new study say that the Earth’s wobble is not a prelude to an impending environmental catastrophe.
The Earth wobbles while it rotates. This is a fact that scientists have long known.
The Earth’s axis of spin has deviated about 34 feet in the past 119 years since 1899. Space-based measurements have also provided confirmation that annually, a few centimeters are added to the drift in the Earth’s axis.
Though humans have played some part in the wobble of the Earth’s spin, new research study quantifies the three main reasons— melting glaciers, different environmental processes, and movement of the Earth’s mantle.
The lead researcher for the study is an Earth system scientist working in Pasadena, California at NASA’s Jet Propulsion Laboratory, Surendra Adhikari.
She said, “We have provided evidence for more than one single process that is the key driver” for altering the Earth’s axis. The study was published in the November issue of the journal Earth and Planetary Science.
To account for three main factors, the research team built a computer model of the physics of the Earth’s spin. A simulation of the polar wobble, as well as the factors contributing to it, is hosted on the JPL website.
Glacial isostatic adjustment, a process that has been going on for the past 16,000 years since the last ice age, is responsible for a third of the Earth’s wobble.
This is around 1.3 inches of axis wobble per year out of the total 4 inches per year as observed over the 20th century. Over thousands of years, glaciers melt and retreat. This alleviates their mass from pushing down on the land underneath. This causes the land to bulge and rise.
The second factor that affects the axis of the Earth’s spin is environmental processes- causing 1.7 inches each year. A particularly important contributor discovered by the researchers is the melting of the Greenland ice sheet.
Erik Ivins, co-author of the study and senior research scientist at JPL said the melting of the ice sheet released a large amount of water into the oceans, causing its mass to be redistributed.
As for the last factor accounting for the last third of the Earth’s wobble, Adhikari and his team found it in the Earth’s mantle.
This inner layer of the Earth moves by a process called convection- a vertical motion where hotter material located closer to the core rises while cooler material moves downward and sinks.
Ivins and Adhikari said that it’s important to note that the Earth’s wobble isn’t some sign pointing to any kind of environmental calamity. However, the research has given scientists a way to decipher the Earth’s mass and where it’s going. An example can be seen in how Greenland’s melt has pushed the drift eastward and largely contributed to changing the axis location over the past 15 years.
Ivins said, “That fact is important for climate scientists because they can understand, in a global sense, which are the most important mass transports that are going on today.”
Source: Live Science